I've just joined this forum so please excuse any violation of norms or conventions. If there's "rules of conduct" page, please point me to it.

I've been fiddling with sudoko for some months now, and have recently experiment with a solving technique that I've often seen hinted at but never seen directly applied.

Here's the idea briefly. I'll elaborate if it turns out to be worthwhile.

You can apply to a puzzle any consequences that follow from all of N mutually exclusive conditions. For example, suppose we know square 1,1 can contain only 5 or 7. Further suppose that if 5 is put in 1,1, 3 is removed as a candidate from square 1,9. And still further suppose that if 7 is put in square 1,1 3 is also removed as a candidate from square 1,9. We know that we can eliminate 3 as a candidate from square 1,9.

I've automated this approach, and found that it's solved all puzzles I've run through it, considering at most 5 squares, each with two possible values. In general, the technique could be taken much further; it could, for example consider a row with could have the value 5 in one of N possible squares, etc. But that hasn't been necessary.

Carried out by a human, this approach could be very labor-intensive (I've done it with software). Also, it could be categorized as "trial-and-error" though I think that's debatable. Labor-intensive yes, trial and error, I might argue.

Anyway, I'm writring this because I'd appreciate any comments, puzzles to run through the technique, or pointers to descriptions of similar approaches.

Paul